The present invention relates to an apparatus and method for converting an arbitrary type television signal into a different type television signal, and more particularly to an apparatus and method for converting an arbitrary type television signal to a different type television signal to have plural aspect ratios.
Present television systems differ according to nations and regions. These differences include the number of scanning lines, the aspect ratio of the screen, the scanning method, etc. Furthermore, current television systems have limited resolutions. Accordingly, a television system having better resolution than current systems is being developed. One recently developed television system having excellent resolution is a high definition television system (HDTV) called a MUSE-type, (Multiple Sub-Nyquist Sampling Encoding) which was developed in Japan. The MUSE-type system has 1,125 scanning lines and a screen aspect ratio of 16:9. Accordingly, the present NTSC-type television receiver having 525 scanning lines and a 4:3 screen aspect ratio cannot receive the MUSE-type television signal. Thus, in order to receive the MUSE-type television signal by present NTSC-type television receivers, a television signal converter is required to convert the MUSE-type television signal into the NTSC-type television signal.
The conventional television signal converter for accomplishing the above conversion is disclosed in Japanese laid-open Patent No. Hei 2-291790. According to this disclosure, the conventional television signal converter performs conversion of the scanning line number and interpolation of a television signal having the 16:9 aspect ratio and 1,125 scanning lines, thereby converting it to a television signal having a 4:3 aspect ratio and 525 scanning lines. This conventional television signal converter twice performs the scanning line conversion, scanning line interpolation, and speed conversion, to convert a television signal having an aspect ratio of 16:9 and 1,125 scanning lines into a television signal having a predeterminedly different aspect ratio and, say, 350 scanning lines.
As a result, the conventional television signal converter has problems in that the signal processing to convert the MUSE-type television signal into an NTSC-type television signal is overly complex. Moreover, circuit construction is also complicated.